Alkylation process with recovery and regeneration of fluorosulfuric acid catalyst

ABSTRACT

The present invention provides an improved alkylation process comprising: contacting an olefin and a paraffin with an alkylation catalyst comprising fluorosulfuric acid, at alkylation conditions, in an alkylation reactor, thereby forming a hydrocarbon phase comprising alkylate reactor product and containing at least a portion of the catalyst; washing the hydrocarbon phase with an acid comprising sulfuric acid to form an acid phase containing fluorosulfuric acid, hydrofluoric acid, and sulfuric acid; contacting the acid phase with water thereby converting at least a portion of the fluorosulfuric acid to hydrogen fluoride and sulfuric acid; removing at least a portion of the hydrogen fluoride from the acid phase by contacting the same with a paraffin such as n-butane thereby forming a hydrocarbon phase containing hydrogen fluoride; treating the hydrocarbon phase with sulfur trioxide to regenerate the fluorosulfuric acid; and recycling at least a portion of the regenerated fluorosulfuric acid to the alkylation zone to be used as an alkylation catalyst therein.

United States Patent [191 Parker et ALKYLATION PROCESS WITH RECOVERY*Dec. 9, 1975 Primary Examiner-Delbert E. Gantz Assistant Examiner-G. J.Crasanakis Attorney, Agent, or FirmA, D. Litt; John W. Ditsler [75]Inventors: Paul T. Parker, Baton Rouge, La.;

Ivan Mayer, Summit, NJ. [73] Assignee: Exxon Research & Engineering [57]ABS CT Company, Linden, NJ. The present invention provides an improvedalkylation N I process comprising: contacting an olefin and a paraf- 1we $23 552: 52232 3522 990 fin with an alkylation catalyst comprisingfluorosulfuhas been disghimed ric acid, at alkylation conditions, in analkylation reac- I tor, thereby forming a hydrocarbon phase comprising[22] Filed: July 30, 1973 alkylate reactor product and containing atleast a por- [211 No 383 581 tion of the catalyst; washing thehydrocarbon phase with an acid comprising sulfuric acid to form an acid[44] Published under the Trial Voluntary Protest phase containingfluorosulfuric acid, hydrofluoric Program on January 28, l975 asdocument no. acid, and sulfuric acid; contacting the acid phase with Bwater thereby converting at least a portion of the Related ApplicationDam fluorosulfuric acid to hydrogen fluoride and sulfuric [63]Continuation of Ser No 236 737 M h 2l I974 a-cid; removing a? laast aportion of the hydrggen flu'o Pat No 3 766 293 ride from the acid phaseby contacting the same with a paraffin such as n-butane thereby forminga hydro- 52 Cl n carbon phase containing hydrogen fluoride; treating EInL GL2 I I g g gi the hydrocarbon phase with sulfur trioxide toregener- 58 m f S ate the fluorosulfuric acid; and recycling at least a1 0 ch 260/683'58 portion of the regenerated fluorosulfuric acid to the[56] Reierences Cited alkylation zone to be used as an alkylationcatalyst th UNITED STATES PATENTS mm 3,766,293 10/1973 Parker et al.260/683.58 14 Claims 1 Drawing Figure I2 I 26 23 y a o Auvunon 24REACTOR m-5R seamen m r 22 :4 PARAFFIN Ho '8 f .40 36 20 M 32 3e cmvsr L61 onsoeurmzzn ea 5: as 44 55 e2 so convsnsmu smwsa town a I ta -l 52 fALKYLATION PROCESS WITH RECOVERY AND REGENERATION OF FLUOROSULFURIC ACIDCATALYST This application is a continuation of US. Ser. No. 236,737,filed Mar. 21, 1974, now US. Pat. No. 3,766,293, issued Oct. 16, 1973.

BACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates to a hydrocarbon conversion process. Moreparticularly, the invention relates to an improved alkylation processemploying a catalyst comprising fiuorosulfuric acid wherein thefiuorosulfuric acid present in the alkylation product is recovered andregenerated.

2. Description of the Prior Art Acid catalyzed hydrocarbon conversionprocesses comprising contacting an alkane with an alkene are well known.The reactants are generally contacted in the liquid phase and within abroad temperature range of from about 100 to 100F. with an acid catalystsuch as, for example, sulfuric acid, fiuorosulfuric acid or a halogenacid, such as hydrofluoric acid.

Alkylation proce'ses employing fiuorosulfuric acid as a catalyst aredescribed in US. Pat. Nos. 2,313,103, 2,344,469 and U.l(. Pat. No.537,589. The use ofother acids such as trifluoromethanesulfonic acid asalkylation catalysts has also been described (T. Gramstad and R. N.Haszeldine, J. Chem. Soc., 1957, 4069-79).

A particularly desirable alkylation process is disclosed in copendingUS. Patent application, Ser. No. 201,389, filed Nov. 23, 1971 andassigned to the same assignee as herein. According to an advantageousembodiment of this copending application, the alkylation process isconducted in the presence of a catalyst mixture comprising: l) a majoramount of strong acid catalyst comprising a fiuorosulfuric acid and, ifdesired, one or more other strong acids such as another halosulfuricacid (XSO H) or trahalomethanesulfonic acid (CX SO H); in combinationwith (2) a minor amount of one or more catalyst promoters comprisingwater; aliphatic and cycloaliphatic alcohols, thiols, ethers andthioethers; aliphatic, cycloaliphatic and aromatic sulionic andcarboxylic acids and their derivatives; or inorganic acids.

Typically, according to this process, a suitable C C terminal orinternal olefin, such as butene-l, is reacted with a straight orbranched chain C -C paraffin, such as isobutane, in the presence of thefiuorosulfuric acid catalyst and a promoter such as water. The reactionis advanced by maintaining the reactants and catalyst in intimatephysical contact. After a sufficient period of time, thecatalyst/promoter phase, hereinafter referred to as the acid phase, isallowed to settle from the hydrocarbon phase and is then withdrawn. Thispartially spent catalyst may be partially or wholly recycled to thereactor, or a portion thereof can be regenerated or reactivated by anysuitable treatment and returned to the alkylation reactor.

While the solubilities of fiuorosulfuric acid and hydrofluoric acid inthe hydrocarbon phase are small in relative terms, nonetheless, economiclosses are sustained due to the incomplete physical separation of theacid and hydrocarbon phases. Furthermore, the acid is highly corrosive,especially at high temperatures, and more than minimal amounts must beprevented from passing to further processing stages, such as theconventionally employed deisobutanizer tower. Yet further, the presenceof small amounts of sulfur and fluorine in hydrocarbon fuels posepotential pollution problems, and every effort must be made to not onlydecrease present levels of pollutants, but also to prevent the creationof further potential pollutants which may ultimately be introduced intothe environment. Still further, prolonged contact with the acid maycause degradation of the alkylate product and must be avoided.

SUMMARY OF THE INVENTION Accordingly, it is an object of the presentinvention to provide an improved alkylation process employing a catalystcomprising fiuorosulfuric acid wherein at least a portion of the aciddissolved and/or dispersed in the alkylate reactor product is recoveredand regenerated.

This and other objects are accomplished by the present invention whichprovides an improved alkylation process comprising: contacting an olefinand a paraffin with an alkylation catalyst comprising fiuorosulfuricacid, at alkylation conditions in an alkylation reactor thereby forminga hydrocarbon phase comprising alkylate reactor product and containingat least a portion of the catalyst; washing at least a portion of thehydrocarbon phase with an acid comprising sulfuric acid forming an acidphase containing fiuorosulfuric acid, hydro fluoric acid and sulfuricacid and a hydrocarbon phase containing alkylate reactor product;contacting the acid phase with water thereby converting at least aportion of the fiuorosulfuric acid to hydrogen fluoride and sulfuricacid; removing at least a portion of the hydrogen fluoride from the thustreated acid phase by contacting the same with a paraffin to therebyform a hydrocarbon phase containing hydrogen fluoride; treating the thusformed hydrocarbon phase with sulfur trioxide to regenerate thefiuorosulfuric acid; and using at least a portion of the regeneratedfiuorosulfuric acid as an alkylation catalyst. In a preferredembodiment, the regenerated acid catalyst is recycled to the alkylationzone.

The invention will become more apparent in view of the ensuingdiscussion and accompanying drawing which schematically represents oneembodiment of the present invention. A detailed description of thecatalyst recovery and regeneration system of the instant invention ispresented below in conjunction with the discussion of the drawing.

According to the present invention, an alkylation process is conductedin the presence of a catalyst mixture comprising fiuorosulfuric acid. Ina preferred embodiment, the catalyst comprises: (1) a major amount of astrong acid catalyst comprising fiuorosulfuric acid and, if desired, oneor more other strong acids such as another halosulfuric acid (XSO I-I),trihalomethanesulfonic acid (CX SO H) or mixtures thereof; incombination with (2) a minor amount of one or more catalyt promoterscomprising water; aliphatic and cycloaliphatic alcohols, and ethers;aliphatic, cycloaliphatic and aromatic sulfonic and carboxylic acids andtheir derivatives; or inorganic acids.

The alcohols preferably contain 1 to 10 carbon atoms and l to 10hydroxyl groups per molecule. The lower molecular weight saturatedalcohols are most preferred and desirably contain 1 to 7 carbon atomsand 1 to 4 hydroxyl groups per molecule. The ethers are preferablysaturated and contain 2 to 10, preferably 2 to 5,

carbon atoms per molecule. In the latter instance, while monoethercompounds are preferred promoters, compounds containing up to 3 or morealkoxy groups are also contemplated. The sulfonic and carboxylic acidspreferably contain 1 to 10, most preferably l to 7 carbon atoms permolecule. In addition, the acids can be substituted with one or morecarboxy or sulfo groups. The acid derivatives include the esters andanhydrides and preferably contain 2 to 20, most preferably 2 to 10,carbon atoms per molecule.

The aliphatic, cycloaliphatic and aromatic portions of theaforementioned promoters optionally can be substituted with a variety ofsubstituents such as halogen atoms, and such groups as hydroxy, C to Calkoxy, C to C perhaloalkyl, C to C carboalkoxy, carboxy, C to Chydrocarbyl, preferably C to C alkyl or C to C cycloalkyl, orcombinations thereof.

The inorganic acids will, in general, be less acidic than the strongacid component of the catalyst system and desirably will have H values,i.e. log h (Hammett acidity function), greater than about ll (see Gould,E. Mechanism and Structure in Organic Chemistry, New York, Holt,Rinehart and Winston, 1959, 106). Preferred inorganic acids contain 1 to4 hydroxyl groups per molecule.

The catalyst promoter may be used effectively with a wide variety ofstrong acids. Examples of strong acid components of the strongacid/promoter catalyst system which can be used in combination withfluorosulfuric acid are other halosulfuric acids, such as chlorosulfuricacid and bromosulfuric acid; trihalomethanesulfonic acids, such astrifluoromethanesulfonic acid, trichloromethanesulfonic acid andtribromomethanesulfonic acid; or mixtures thereof and the like. Thepreferred strong acid portion of the catalyst system includesfluorosulfuric acid, alone or in combination withtrifluoromethanesulfonic acid. In addition, the phosphorus analog oftrihalomethanesulfonic acid, i.e., trihalomethanephosphonic acid, may bean effective strong acid.

Illustrative, non-limiting examples of useful promoter compositionsinclude:

water methanol ethanol n-propanol isobutanol 3-chloro-2 methyl- 1-butanol 6-mercapto-4-methoxy-2hexanol2,2-dimethyl-4-methylthio-3-perfluoromethyll hexanol4,4-dimethyl-3-phenolthiol heptanol S-carbethoxy-4,4-dimethyl-l-pentanol2-decanol cyclopropanol cyclopentanol 2-chlorocyclohexanol cyclodecanoll ,2-dihydroxyethane l ,2,3-trihy droxypropane 2,4,5-trihydroxypentane1,3 ,S-trihydroxycyclohexane 1 ,2-dihydroxycyclooctane pentaerythritolmethylsulfonic acid 2-chloroet hylsulfonic acid propylsulfonic acidethyl propanesulfonate methyl-Z-phenoxyethanesulfonate benzenesulfonicacid formic acid acetic acid propionic acid butyric acid hepanoic aciddecanoic acid benzoic acid ethyl acetate methyl butanoate propyldecanoate ethyl benzoate 2-chlorobutanoic acid 2-hydroxy-5methylhexanoicacid phenyl acetate trifluoroacetic acid 3,3,3-trifluoropropionic acidacetic anhydride propionic anhydride ethanoic anhydride butanoicanhydride oxalic acid malonic acid phthalic acid diethylmalonate1,2,3-tricarboxypropane dimethyl ether diethyl ether diphenyl etherdipropyl ether dioctyl ether ethyl methyl ether chloromethyl ethyl etherdicyclobutyl ether dinonyl ether decyl nonyl ether l-methoxycyclopentylethyl ether ethylene oxide phosphoric acid phosphorous acid sulfuricacid sulfurous acid monofluorophosphoric acid difluorophosphoric acidorthophosphoric acid pyrophosphoric acid polyphosphoric acid Preferredcatalyst promoters contain either a hydroxy group, such as alcohols or ahydroxy group precursor, such as ethers which cleave to form alcoholsunder the acidic conditions of the subject invention. Of these, the mostpreferred compounds are the alcohols and water. It is noted that whilethe catalyst promoter and strong acid are desirably premixed prior tointroduction into the reactor, the process also contemplates the in situformation of the catalyst system.

Aromatic compounds are generally not preferred as catalyst promoterssince competitive sulfonation of the aromatic ring occurs under thealkylation reaction conditions. However, if the aromatic nuclei aresufficiently deactivated, with regard to electrophilic substitution,they are then effective promoters. Thus, for example, electronwithdrawing groups such as --CO0H, SOJ-l, --COOR and the like arebelieved to sufficiently deactivate aromatic rings to permit their usein the sub ect process. In general, aromatic ring substituents withHammetto and 8 values equal to or greater than +0.01 are acceptable. Fora more detailed discussion of the Hammett equation and electrophilicaromatic substitution in general, see Mechanism and Structure in Orgam'cChemistry, by Edwin S. Gould, 195 9, Holt, Rinehart & Winston, lnc., pp.220-227 and 412-463. Additionally. it is noted that highly basicmaterials such as amines, for example triethylamine, cannot generally beused in the concentration range of the subject process due to reactionwith the strong acid.

While inorganic acids such as I-ICl, I-IBr and HI may be used aspromoters, their effectiveness is diminished by their tendency to formstable halides with the olefin reactants. Halide formation, however, isnot an important problem with HF. Additionally, oxidative acids such asI-INO; and l-IClO, cannot be used as promoters due to oxidative sidereactions with the olefins.

It has been found that the concentration of the promoter in thetwo-component catalyst system is an important variable in the productionof high quality alkylate. The promoter is admixed with the strong acidcatalyst component in amounts ranging from about 5 to 45 mole based onacid, preferably to 30 mole and still more preferably to 25 mole forexample mole In some instances, however, it may be desirable to usesomewhat lower or higher amounts of promoter where, for example,increased catalyst activity or selectivity is desired.

In the case of hydroxyl-containing promoters, (or promoters containinghydroxyl precursors, i.e. latent hydroxyl groups) concentration of thepromoter in the total catalyst may fall below the above-specifiedconcentration range, i.e. 5 to 45 mole It appears that the promotingefficiency of hydroxy compounds is directly related to the overallnumber of hydroxyl groups or latent hydroxyl groups present permolecule. Thus, ethanol with one hydroxyl group should have promoteractivity similar to 0.5 mole of ethylene glycol with two bydroxylgroups. Hence, as the number of hydroxyl groups or latent hydroxylgroups per molecule of promoter increases, the required concentration ofthe total compound in the catalyst will decrease.

Although the broad concentration ranges are generally independent of thetype of promoter used, the preferred or optimal range will varydepending on the structure of the promoter, the reaction temperature,the concentration of olefin in the feed and the olefin space velocity.

In addition to classical alkylation processes as hereinabove described,the subject invention may also include self-alkylation processes. The CC branched chain olefins and C -C isoparaffins are preferred reactants.The process is generally conducted in the liquid phase where by theisoparaffin is dimerized and the olefin is saturated producing analkylate-type product of high quality. Self-alkylation processes aregenerally described in U.S. Pat. No. 3,150,204. Undesired side reactionsare minimized using the above-described catalyst systems, therebyproviding high yields of the desired products.

In general, the amount of olefin contacted with the catalyst can rangefrom about 0.05 to 1000 volumes of olefin per hour per volume ofcatalyst inventory in the reactor (v/v/hr.), i.e. olefin space velocity.Preferably, the olefin space velocity ranges from about 0.05 to 10.0v/v/hr., and still more preferably from about 0.05 to 1.0 v/v/hr., e.g.0.] v/v/hr. The volume of total catalyst in the reaction mixture oremulsion (when liquid phase operations are used) in the reactor canrange from about 40 to volume based on total reaction mixture andpreferably from about 50 to 70 volume The isoparaffin concentration,including alkylate, 1n the hydrocarbon phase (in a liquid phase process)can range from 40 to 100 volume based on the total volume of thehydrocarbon phase and preferably from 50 to volume Such isoparaffinconcentrations can be maintained by recycling unreacted isoparaffin tothe reactor.

Suitable olefinic reactants include C -C tenninal and internalmonoolefins such as ethylene, propylene, isobutyline, butene-l,butene-2, trimethylethylene, the isomeric pentenes and similar highermonoolefinic hydrocarbons of either a straight chain or a branched chainstructure. Preferably the C -C monoolefins are used, although the highlybranched C -C monoolefins may also be used. The reaction mixtures mayalso contain some small amounts of diolefins. Although it is desirablefrom an economic standpoint to use the normally gaseous olefins asreactants, normally liquid olefins may be used. Thus the inventioncontemplates the use of reactable polymers, copolymers, interpolymers,and the like, of the above-mentioned olefins, such as, for example, thediisobutylene and triisobutylene polymers, the codimer of normalbutylene and isobutylene, of butadiene and isobutylene, and the like.Mixtures of two or more of the olefins above described can be used asthe process feedstock.

The instant process is particularly adapted to refinery alkylationprocesses, and contemplates the use of various refinery cuts asfeedstocks. Thus, C C C, and/or C olefin cuts from thermal and/orcatalytic cracking units; field butanes which have been subjected toprior isomerization and partial dehydrogenation treatment; refinerystabilizer bottoms; spent gases; normally liquid products from sulfuricacid or phosphoric acid catalyzed polymerization and copolymerizationprocesses; and products, normally liquid in character, from thermaland/or catalytic cracking units, are all excellent feedstocks for thepresent process. Such feeds are preferably dried to control excess waterbuildup, i.e. about 5 to 15 ppm (weight) of water before entering thereactor.

The hydrocarbon feedstocks that are reacted with the olefins desirablycomprise branched chain C -C paraffins such as hexane, butane and thelike, and, preferably, C -C isoparaffins such as isobutane, isopentane,isohexane and the like. While open chain hydrocarbons are preferred,cycloparaffins may also be used.

Catalyst that is carried over in the akylate reactor product isrecovered and regenerated according to the process of the inventionwhich is discussed in more detail below.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a flow scheme of theinvention.

Referring now to the drawing in detail, the olefin which is introducedvia line 2 is, preferably, admixed with the paraffin from lines 4 and 6before introducing the combined stream into the reactor 8. If desired,however, the olefin and paraffin streams can be fed directly into thereactor 8. The olefin concentration in the feed ranges from 0.5 to 25volume based on total feed and preferably below 10 volume Translatedinto volume ratios, high volume ratios of paraffin to olefin rangingfrom 10:1 to 200:1 or higher are preferred, although somewhat lowerratios may be used, i.e. 3: l. Correspondingly high volume ratios ofparaffin to olefin are also desired within the reaction zone.Preferably, the paraffin/olefin ratio therein ranges from about 20:] to2,00021 or higher. The catalyst mixture comprising fluorosulfuric acidand a promoter such as water is introduced into the reactor via line 10and additional water can be introduced into the reactor via line 12:

The process may be carried out either as a batch or continuous type ofoperation, although it is preferred for economic reasons to carry outthe process continuously. it has been generally established that inalkylation processes, the more intimate the contact between thefeedstock and the catalyst the better the yield of saturated productobtained. With this in mind, the present process, when operated as abatch operation, is characterized by the use of vigorous mechanicalstirring or shaking of the reactants with the catalyst.

in continuous operations, as that of the embodiment shown in thedrawing, the reactants may be maintained at sufficient pressures andtemperatures to maintain them substantially in the liquid state and thencontinuously forced through dispersion devices into the reaction zone.The dispersion devices may be jets, porous thimbles and the like. Thereactants are subsequently mixed with the catalyst in the reactor 8 byconventional mixing means (not shown) such as mechanical agitators andthe like. While the alkylation reaction can be carried out at atemperature within the range of from about -80 to +100F., fairly lowreaction temperatures, preferably within the range of from about -80, to70F, and most preferably within the range of from about to about +40F.,are usually employed. Where the reaction is carried out at temperaturesabout +1 OF., or higher it is necessary that the reaction be conductedunder superatmospheric pressure, if both the reactants and the catalystare to be maintained substantially in a liquid state. Typically, thealkylation reaction is conducted at pressures varying from about 1 to 20atmospheres.

In general it is preferable to employ pressures sufficiently high tomaintain the reactants in the liquid phase, although a vapor phaseoperation is also contemplated. Autorefrigerative reactors and the likemay be employed to maintain liquid phase operation. Al though it ispreferred to run the reaction neat, solvents or diluents may beemployed, if desired.

After allowing sufficient residence time for the reaction to progress,typically on the order from about five minutes to one hour or more, thereaction mixture is withdrawn from the reactor via line 14 and passedinto a settler 16. The reaction mixture will separate in the settler 16into a heavy acid phase containing the fluorosulfuric acid and promoterand a hydrocarbon phase containing the alkylate product along withsmaller amounts of fluorosulfuric acid, hydrogen fluoride and waterwhich are dispersed and/or dissolved in the alkylate product. The acidphase is withdrawn from the settler 16 via line 18 and at least aportion thereof can be recycled to the reactor 8 via line 10 or chargedto another alkylation reactor, if desired. A purge stream 20 may bewithdrawn from line 18 and passed to a regeneration stage which will bediscussed in more detail hereinbelow. The hydrocarbon phase is withdrawnfrom settler 16 via line 22 and passed into a scrubber 24 wherein it isintimately contacted with sulfuric acid which is introduced via line 16.The sulfuric acid is preferably concentrated being, 99.5 to 100% H 80but somewhat more dilute acid (97-98%) can also be used withoutsubstantial detriment to the efficiency of the process. Make-up sulfuricacid is introduced into line 26 via line 25.

As previously noted, the hydrocarbon phase contains dissolved and/ordispersed fluorosulfuric acid, water, hydrogen fluoride from partialdissociation of the acid, and other acidic materials such as sulfurdioxide, etc. It has been found that the acid materials which aredissolved and/or dispersed in the hydrocarbon phase can be effectivelyremoved by scrubbing the hydrocarbon phase with concentrated sulfuricacid. The manner of scrubbing may be by any conventional means, such asby passing the sulfuric acid and hydrocarbons through a mixing orifice,a countercurrent contacting tower or by injecting them into acentrifugal pump, etc., as long as intimate contact between thehydrocarbon phase and the sulfuric acid is attained. The ratio of acidto hydrocarbon is not critical, but can vary from about 5 to of thehydrocarbon stream. The ratio is controlled by recycling acid from line40 through line 41 to line 26. The temperature for scrubbing generallyranges from about 20 to F. and the pressure may be any pressure fromatmosphere to about 500 psig. The resulting phases are settled aftercontacting.

While the sulfuric acid scrubber removes most of the acidic materialsfrom the hydrocarbon phase, trace amounts of acid materials, primarily H80 remain in the effluent from the scrubber. The effluent hydrocarbon iswithdrawn from the sulfuric acid scrubber via line 28 and is passed toan alkaline treater 30 which frees the hydrocarbon phase of theremaining trace amounts of acid. The alkal ne treater may be of anyconventional construction, such as the type wherein solid alkali metaloxides such as potassium oxide and sodium oxide react with sulfuric acidto form potassium sulfate, potassium fluoride, sodium sulfate, sodiumfluoride and water which are removed from the hydrocarbon phase, such asby line 32, in the drawing. The hydrocarbon phase is then removed fromthe alkaline treater via line 34 and passed to a deisollutanizer tower36. The deisobutanizer 36 may be a deisobutanizing tower of conventionalconstruct on to separate the hydrocarbon phase into an isobutane stream,which can be withdrawn by line 6 for recycle to the alkylation reactor8, and the fina product of the alkylation process wh ch is withdrawn v alive 38. If desired, the isobutane need not be recyc ed to the reactorand can be sent on to further processi g elsewhere.

Returning now to scrubber 24, the sulfuric acid stream is withdrawntherefrom via line 40 and, if desired, combined with the purge stream20. The combined stream flows via line 42 to a conversion tower 44wherein sufficient water is injected via line 46 to convert thefluorosulfuric acid to free hydrogen fluoride and sulfuric acidaccording to the reaction:

in one embodiment of the invention, it may be desirable to add up to amole of water in excess of the stoichiometric amount required.Preferably, less than about 0.5 mole excess water is used. The resultingstream of water, hydrogen fluoride, sulfuric acid and fluorosulfuricacid is removed from the conversion tower 44 via line 48 and passed tostripper 50 wherein the hydrogen fluoride is stripped from this streamby intimately contacting it with a stream of hydrocarbons introduced vialine 52. Preferably n-butane is used. it is noted that, in oneembodiment of the invention, the

conversion tower and stripper comprise a single vessel. In the uppersection 54 of the stripper 50 the hydrogen fluoride is reacted withsulfur trioxide according to the reaction:

HF S HSO F heat.

The sulfur trioxide, which is introduced via line 56, thus regeneratesthe fluorosulfuric acid catalyst which, together with the hydrocarbonand some water is taken overhead via line 58, condensed in a condenser60, and passed to separator 62 wherein the fluorosulfuric acid isseparated from the hydrocarbons present in the stream. The regeneratedfluorosulfuric acid stream containing water is withdrawn from theseparator via line 64 and at least a portion thereof is combined withthe recycle stream 18 for return to the reactor 8 via line 10. Thehydrocarbon phase is removed from the separator 62 via line 66. At leasta portion of the hydrocarbon is recycled to line 22 for additionalprocessing or to tower 44 and stripper 50 via lines 55, 63, 43 and 45for temperature control purposes. In addition some of the hydrocarboncan be used as part of the stripping agent in stripper 50, being introduced therein via line 52. Additional hydrocarbon stripping agent can beintroduced into the stripper via line 53. The sulfuric acid sludge canbe removed from the bottom of the regeneration tower 50 via line 68 andsent for sulfuric acid regeneration (not shown) for carbon removal andreconcentration, or it can be discarded. The stripper 50 is generallyoperated at temperatures ranging from about 120 to 300F., preferably 150to 200F., and pressures from about 30 to 100 psig; however, it iscustomary to adjust the temperatures and pressures to maintain theproper phase relationshi s in the process.

While any saturated hydrocarbon can be used for the stripping operationin tower 50, it has been found to be highly advantageous to employn-butane because, when contacted with the hydrogen fluoride andfluorosulfuric acid in the tower, the n-butane is partially isomerizedto the desired isobutane used as feed to the alkylation reactor.Accordingly, the hydrocarbon phase removed from separtor 62 containsconsiderable isobutane which after scrubbing can be removed by thedeisobutanizer 36 and passed via line 6 to be mixed directly with theolefin feed in line 2.

The following examples are presented for the purpose of more clearlyillustrating the present invention. Unless otherwise specified, allpercentages and parts are by weight.

EXAMPLE 1 A sample of a commercial alkylate containing fluorosulfuricacid was divided into two portions, part A and part B. Part A was washedthoroughly with dilute sodium hydroxide and the aqueous phase was thenseparated and analyzed for sulfate. The amount of sulfate was found tobe equivalent to 0.121 weight percent fluorosulfuric acid based on thehydrocarbon. Part B was stirred with concentrated sulfuric acid for 30minutes and the mixture was allowed to settle. The hydrocarbon phase wasseparated and washed with excess, dilute sodium hydroxide. The aqueousphase obtained from this washing, was separated and analyzed forsulfate. The amount of sulfate was found to be equivalent to 0.016weight percent fluorosulfuric acid based on the hydrocarbon. Thus, it isseen, according to this example, that approximately 91.7% of thefluorosulfuric acid was removed from the hydrocarbon.

EXAMPLE 2 Approximately 1600 grams of n-hexane containing fluorosulfuricacid was divided into two parts, part A and part B. Part A was washedwith excess dilute sodium hydroxide and the aqueous phase separated andanalyzed for sulfate. The sulfate was found to be present in an amountequivalent to 0.632 weight percent fluorosulfuric acid, based onhydrocarbon. Part B was pumped through 100 cc of vigorously stirred(500-550 rpm), concentrated (97-98%) sulfuric acid at room temperatureat a rate of about 8.7 v/v/hr. based on the acid. A total of about 1,000cc of the n-hexane was pumped through the acid. The collected, scrubbednhexane was washed with excess dilute sodium hydroxide, and theresulting aqueous solution was then separated and analyzed for sulfate.The amount of sulfate was found to be equivalent to 0.0037 weightpercent fluorosulfuric acid based on hydrocarbon. Thus, it is seen thatapproximately 99.5% of the fluorosulfuric acid was removed from thehydrocarbon by treatment with the sulfuric acid.

EXAMPLE 3 A mixed olefin and fresh isobutane feed comprising nC H C H iCH and n-C4H at a total flow rate of 10,000 B/D is combined with arecycle isobutane stream comprising n--(I H i-CJ-l and nC H at a flowrate of 28,560 B/D and then passed into an alkylation reactor at a totalflow rate for the combined feed stream of 38,560 B/D, wherein it ismixed with a catalyst mixture of mol fluorosulfuric acid and 20 molwater based on acid. The olefin space velocity, based on the acid, ismaintained at about 0.27 v/v/hr. The autorefrige rated reactor ismaintained at a temperature of about 20F. and a pressure of about 1.1psig. intimate mixing in the reactor is achieved by means of turbinemixers. The volume acid in the reactor emulsion is maintained at about50%.

The alkylation reactor product, 37,055 BID, containing about 70 vol.isobutane, is passed to a settler where it is separated from about37,055 B/D of catalyst into a hydrocarbon phase and an acid phase. Thehydrocarbon phase contains about 600 PPM(w) fluorosulfuric acid andabout 200 PPM (w) hydrogen fluoride. Of the acid phase, about 37,045 B/Dis recycled to the reactor and about l0 B/D, containing fluorosulfuricacid and sludge is purged and passed to the catalyst regenerator. Thehydrocarbon phase is passed through a mixing orifice with about 100 B/Dor less make up concentrated sulfuric acid, the total acid flow rate(fresh cycle) being about 1,860 B/D, i.e. L760 B/D is recycled, to causeintimate mixing of the hydrocarbon phae and the sulfuric acid. As aresult of the mixing most of the fluorosulfuric acid and hydrogenfluoride are dissolved in the sulfuric acid phase.

The acid and hydrocarbon phase are separated by gravity settling.'Thesulfuric acid phase, containing the hydrogen fluoride and fluorosulfuricacid, is combined with the purge stream from the settler and passed intoa fluorosulfuric acid regeneration tower. The hydrocarbon phase removedfrom the scrubbing operation contains trace amounts of acid which areremoved by contacting the hydrocarbon phase with solid potassium oxideand sodium oxide. This deacidified hydrocarbon phase is then passed to adeisobutanizer. The combined acid stream, comprising the purge streamfrom the settler and the acid phase from the scrubber, is passed intothe lower portion of the fluorosulfuric acid regeneration tower whereinit is mixed with liquid n-butane at a temperature of about l75-250F.Vigorous mixing is achieved by means of liquid butane vaporization.

In the regeneration tower, the n-butane is partially isomerized toisobutane and the fluorosulfuric acid reacts with water to form freehydrogen fluoride and sul furic acid. The hydrogen fluoride, someremaining fluorosulfuric acid, and the isobutane form a gaseous phasewhich passes upward through a series of trays to the upper portion ofthe tower wherein sulfur trioxide gas or liquid is introduced and reactswith the hydrogen fluoride to form fluorosulfuric acid.

The net effect of the reactions taking place in the tower is thegeneration of heat; accordingly, heat must be continuously removed fromthe reactor. Heat removal and separation of the fluorosulfuric acid aresimultaneously achieved by withdrawing the gaseous phase from the top ofthe tower and passing it through a condenser to provide a combinedstream at a temperature of about 100F. and a pressure of about 60 to 70pisg. This combined and cooled stream is then passed into a separatorfrom which the fluorosulfuric acid containing a small amount of water iswithdrawn from the bottom and returned to the alkylation reactor. Thehydrocarbon phase containing considerable amounts of isobutane may beused for cooling the top of the stripper by using it as reflux or may beused as feed to the conversion tower. The deisobutanized hydrocarbonphase which comprises the final alkylation product, is found to containonly about 1-5 PPM fluorosulfuric acid.

It will be apparent to those skilled in the art that many variations andmodifications of the present invention can be made without departingfrom the spirit and scope of the present invention, which has as aprinciple feature the reclaiming ani regeneration of a fluorosulfuricacid catalyst in a hydrocarbon alkylation process.

What is claimed is:

1. An improved alkylation process comprising:

a. contacting an olefin and a paraffin hydrocarbon in an alkylationreactor with an alkylation catalyst comprising fluorosulfuric acid atalkylation conditions to thereby form a mixture of fluorosulfuric acidphase and a hydrocarbon phase containing alkylation reaction product;

b. settling said mixture into said hydrocarbon phase and saidfluorosulfuric acid phase;

c. washing said hydrocarbon phase with an acid comprising sulfuric acidthereby removing at least a portion of the fluorosulfuric acid presentin said hydrocarbon phase;

d. separating a sulfuric acid phase containing said fluorosulfuric acidfrom said hydrocarbon phase containing said alkylation reaction product;

e. contacting said sulfuric acid phase separated in step (d) with waterto form an acid-water mixture thereby converting at least a portion ofthe fluorosulfuric acid contained in said acid phase to hydrogenfluoride and sulfuric acid;

f. stripping hydrogen fluoride from said acid-water mixture of step (e)with a paraffin hydrocarbon thereby forming a hydrocarbon phasecontaining hydrogen fluoride;

g. treating the hydrocarbon phase from step (f) with sulfur trioxide toregenerate fluorosulfuric acid; and

h. withdrawing said regenerated fluorosulfuric acid from said alkylationprocess.

2. The method according to claim 1 wherein a portion of said regeneratedfluorosulfuric acid withdrawn from said process is added to saidalkylation zone to comprise at least a portion of the alkylationcatalyst of step (a).

3. The method according to claim 1 wherein the alkylation catalystcomprises a major amount of said fluorosulfuric acid and a minor amountof catalyst promoter.

4. The method according to claim 3 wherein said catalyst promoter iswater.

5. The method according to claim 1 wherein the paraffin hydrocarbon ofstep (f) is n-butane.

6. The method according to claim 5 wherein the nbutane is at leastpartially isomerized to isobutane by contacting said n-butane with thehydrogen fluoride and the fluorosulfuric acid regenerated in step (g),the resulting isobutane being used as a portion of the paraffin feed instep (a).

7. The method according to claim 1 wherein at least a portion of saidfluorosulfuric acid phase in step (b) is recycled to the alkylationreactor of step (a).

8. The method according to claim 7 wherein at least a portion of saidfluorosulfuric acid phase is withdrawn from the recycled catalyst priorto the same entering the alkylation reactor, the withdrawn acid iscombined with the acid phase from step (d) and the combined acid mixtureof said withdrawn acid and said acid phase is then contacted with wateraccording to step (e).

9. The method according claim 1 wherein the contacting of step (a) iscarried out at a temperature within the range from about 20 to about+40F.

10. The method according to claim 1 wherein the contacting of step (a)is carried out at a temperature within the range of about 20 to about+40F. and the stripping of step (f) is carried out at a temperaturewithin the range from about l20 to about 300F.

l l. The method according claim 1 wherein the washing operation in step(c) is conducted in a countercurrent scrubbing tower.

12. The method according to claim 1 wherein the hydrocarbon phase ofstep (b) contains HF.

13. The method according to claim 1 wherein the acid phase of step (d)contains HF.

14. A process for recovering fluorosulfuric acid in an alkylationprocess comprising:

a. contacting an olefin and a paraffin hydrocarbon in an alkylationreactor with an alkylation catalyst comprising fluorosulfuric acid atalkylation conditions to thereby form a mixture containing afluorosulfuric acid phase and hydrocarbon phase containing alkylationreaction product;

b. settling said hydrocarbon phase from said fluorosulfuric acid phase;

0. washing said hydrocarbon phase with an acid com prising sulfuric acidthereby removing at least a portion of the fluorosulfuric acid from saidhydrocarbon phase and forming a sulfuric acid phase containing saidfluorosulfuric acid and a hydrocarbon phase containing said alkylationreaction product;

d. recovering said fluorosulfuric acid from said sulfuric acid phase;and

e. recovering said alkylation reaction product from step (c).

1. AN IMPROVED ALKYLATION PROCESS COMPRISING: A. CONTACTING AN OLEFINAND PARAFFIN HYDROCARBON IN AN ALKYLATION REACTOR WITH AN ALKYLATIONCATALYST COMPRISING FLUOROSULFURIC ACID AT ALKYLATION CONDITIONS TOTHEREBY FORM A MIXTURE OF FLUOROSULFURIC ACID PHASE AND A HYDROCARBONPHASE CONTAINING ALKYLATION REACTION PRODUCT; B. SETTLING SAID MIXTUREINTO SAID HYDROCARBON PHASE AND SAID FLUOROSULFURIC ACID PHASE; C.WASHING SAID HYDROCARBON PHASE WITH AN ACID COMPRISING SULFURIC ACIDTHEREBY REMOVING AT LEAST A PORTION OF THE FLUOROSULFURIC ACID PHASE; D.SEPARATING THE SULFURIC ACID PHASE CONTAINING SAID FLUOROSULFURIC ACIDFROM SAID HYDROCARBON PHASE CONTAINING SAID ALKYLATION REACTION PRODUCT;E. CONTAINING SAID SULFURIC ACID PHASE SEPARATED IN STEP (D) WITH WATERTO FORM AN ACID-WATER MIXTURE THEREBY CONVERTING AT LEAST A PORTION OFTHE FLUOROSULFURIC ACID CONTAINED IN SAID ACID PHASE TO HYDROGENFLUORIDE AND SULFURIC ACID; F. STRIPPIN HYDROGEN FLUORIDE FROM SAIDACID-WATER MIXTURE OF STEP (E) WITH A PARAFFIN HYDROCARBON THEREBYFORMING A HYDROCARBON PHASE CONTAINING HYDROGEN FLUORIDE; G. TREATINGTHE HYDROCARBON PHASE FROM STEP (F) WITH SULFUR TRIOXIDE TO REGENERATEFLUOROSULFURIC ACID; AND H. WITHDRAWING SAID REGENERATED FLUOROSULFURICACID FROM SAID ALKYLATION PROCESS.
 2. The method according to claim 1wherein a portion of said regenerated fluorosulfuric acid withdrawn fromsaid process is added to said alkylation zone to comprise at least aportion of the alkylation catalyst of step (a).
 3. The method accordingto claim 1 wherein the alkylation catalyst comprises a major amount ofsaid fluorosulfuric acid and a minor amount of catalyst promoter.
 4. Themethod according to claim 3 wherein said catalyst promoter is water. 5.The method according to claim 1 wherein the paraffin hydrocarbon of step(f) is n-butane.
 6. The method according to claim 5 wherein the n-butaneis at least partially isomerized to isobutane by contacting saidn-butane with the hydrogen fluoride and The fluorosulfuric acidregenerated in step (g), the resulting isobutane being used as a portionof the paraffin feed in step (a).
 7. The method according to claim 1wherein at least a portion of said fluorosulfuric acid phase in step (b)is recycled to the alkylation reactor of step (a).
 8. The methodaccording to claim 7 wherein at least a portion of said fluorosulfuricacid phase is withdrawn from the recycled catalyst prior to the sameentering the alkylation reactor, the withdrawn acid is combined with theacid phase from step (d) and the combined acid mixture of said withdrawnacid and said acid phase is then contacted with water according to step(e).
 9. The method according claim 1 wherein the contacting of step (a)is carried out at a temperature within the range from about -20* toabout +40*F.
 10. The method according to claim 1 wherein the contactingof step (a) is carried out at a temperature within the range of about-20* to about +40*F. and the stripping of step (f) is carried out at atemperature within the range from about 120* to about 300*F.
 11. Themethod according claim 1 wherein the washing operation in step (c) isconducted in a countercurrent scrubbing tower.
 12. The method accordingto claim 1 wherein the hydrocarbon phase of step (b) contains HF. 13.The method according to claim 1 wherein the acid phase of step (d)contains HF.
 14. A process for recovering fluorosulfuric acid in analkylation process comprising: a. contacting an olefin and a paraffinhydrocarbon in an alkylation reactor with an alkylation catalystcomprising fluorosulfuric acid at alkylation conditions to thereby forma mixture containing a fluorosulfuric acid phase and hydrocarbon phasecontaining alkylation reaction product; b. settling said hydrocarbonphase from said fluorosulfuric acid phase; c. washing said hydrocarbonphase with an acid comprising sulfuric acid thereby removing at least aportion of the fluorosulfuric acid from said hydrocarbon phase andforming a sulfuric acid phase containing said fluorosulfuric acid and ahydrocarbon phase containing said alkylation reaction product; d.recovering said fluorosulfuric acid from said sulfuric acid phase; ande. recovering said alkylation reaction product from step (c).